Immigration is one of those vexed issues about which most people have an opinion but few know how to fix.
Unsurprisingly, the pendulum of migration policies has swung markedly in the political breeze as different governments have attempted to match patterns with priorities.
Those priorities have likewise changed over the years as the equilibrium between resources and population has shifted and the reality of a radically altered world economy has placed insistent demands on policy-makers and politicians alike.
In today's globalised world, wherein the competition for "human capital" and skilled labour becomes increasingly fierce, no country, it seems, can remain an isolated fortress.
But as many governments will testify, in a world replete with trouble spots there is also no shortage of migrants of the displaced kind, and striking the balance between humanitarian and economic impulses in policy settings is a fraught business.
New Zealand has long operated a points and categories system for migrants according to sought-after skills, qualifications, wealth, health, dependants and so on.
There has been and remains an annual refugee quota, investor migrant categories and, in addition, a fluctuating population of home-grown migrants, some off on their Overseas Experience, others returning.
In this context, the latest measures, announced last week by the Government, continue a directional shift set in motion last year by Immigration Minister Jonathan Coleman.
On Thursday, he announced details of two new "retirement visas" - temporary retirement and parent retirement.
The parent retirement category allows Immigration New Zealand to prioritise high net worth individuals who are already seeking to migrate to New Zealand under the Family Category.
The temporary retirement category creates a two-year permit for people who want to spend some of their retirement in New Zealand, provided they invest here and indemnify the Government against possible health and welfare costs.
Parent retirement visa holders will be required to invest a minimum of $1 million over four years; temporary retirees will have to invest $750,000 over the two-year term of their permit, with the possibility of renewing those permits as long as criteria such as investment funds, income and health insurance continue to be met.
These two policies cement in place a greater emphasis on the investor-migrant categories.
For with the relaxing of rules last year, investors with $10 million can get residency in three years without any English skills or business experience or age limit, while being required to remain in the country for a fifth of every year.
In addition, migrants willing to invest $1.5 million now also get residency provided they meet language and business experience requirements.
Since these changes, there have been 99 expressions of interest by prospective migrant investors which, according to Dr Coleman, shows a "healthy interest" in New Zealand as a business destination.
There is good reason to hope that the minister is correct in this.
New Zealand needs inward investment to broaden and underpin economic activity and hence growth, and there is little solid evidence to suggest he is wrong.
However, evidence of the extent to which investor-migrants have settled and contributed in the long term in this country during the past decade or so remains largely anecdotal, as do the tales of those who have arrived, "invested" in large houses, taken advantage of the state education and health services for their families, then sold up and moved out again - sometimes migrating "through the back door" to Australia.
Solid research is required to gauge, assess and finesse the effectiveness of such policies.
The Government is rightly taking a hard-headed look at the domain - New Zealand is not so wealthy as to be able to offer refuge to thousands of migrants who bring little other than "diversity" to their new country, but neither should it push these policies so far that, in effect, the prize of New Zealand citizenship is being sold to the highest bidder.
There are, after all, many values - honesty, pride, diligence, community-mindedness, intelligence, aspiration, entrepreneurialism among them - besides an already accumulated wealth that will colour the future contribution of any migrant, including those in the new parent and temporary retirement categories, to his or her adopted country.
Dr Coleman and the National-led Government are evidently determined to implement immigration policies that pay.
The ambition is laudable, but wealth is relatively easy to measure, other desirable qualities less so.
A degree of care is required.
